Have prepare mask drawing do position mapping

Split out prepare_for_direct_mask_drawing from
prepare_for_mask_drawing. Move the direct mask positioning
code into prepare_for_direct_mask_drawing.

Bug: skia:14065
Change-Id: Ief21c9e793fba4828bfdd317892310226d101771
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/635182
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
2 files changed